pete, on the investigative side, i know that janet napolitano testified this morning and play a little bit of her caution to everyone. >> the investigation is proceeding apace and it just, you know, this is not an ncis episode. sometimes you have to take time to properly you know, put the chain together to identify the perpetrators. >> and pete said something that you as an experienced justice and homeland security correspondent know all too well. the pieces are being put together. tell us where we stand today. >> they're moving on several tracks, andrea. the photo track may be among the most promising. the government believes it has identified two people it wants to find, identify, find and interview. that have been seen acting suspiciously, carrying backpacks, duffle bags that are heavy. they think the bomb weighed 20 pounds, so they're interested in talking to them. they may or may not show us pictures of that. there was some back and forth on this the last 24 hours, about the advantages and disadvantages and we were thinking we might hear about it this afternoon. we may not. that i